In a medieval dungeon, a prince has been imprisoned for more than twenty years for an alleged crime. His testimony supports some fantastic facts, which is why he is identified as a person possessed by the devil or insane. A sorcerer, spokesman for the King, visits him periodically to achieve his improvement, so that the prince is released and is in a position to become the future king. The prince is not willing to deny what he saw. But the sorcerer offers him a deal that puts the values, truth and justice of the entire kingdom at stake. Príncipe Constante reveals the true story behind a lie that accompanied us from our childhood until today. But now the truth is known.

This time, the "exterminators" must confront a secret organization conducting a diabolical experiment: transforming a fighter into an indestructible man through a series of bionic implants. To investigate their scheme, Colonel Morris assigns Guillermo and Héctor Echavarria, but they are joined by Nico, an orphaned boy eager to become part of the Eagle Command.